1. Field of the Invention
The present invention relates to a surface-mounted type electronic component for surface-mounting on a printed circuit board or on a hybrid integrated circuit (HIC), which are used for an electronic equipment, and a manufacturing method of the electronic component.
2. Description of the Related Art
There are various passive components such as coil components configuring inductor elements or common mode choke coils or capacitor components, used as electronic components surface-mounted on electronic equipments such as computers or mobile telephones.
As for the coil component for example, known are a line-wound type coil component with a ferrite core and a copper wire wound around the ferrite core, a laminated type coil component with laminated magnetic sheets made of such as a ferrite and a coil conductor pattern formed on a surface of each sheet, and a thin-film type coil component with insulation films and thin metal coil conductors alternately laminated on each other using thin-film fabrication technology.
Japanese patent publication Nos. 8-203,737 and 2002-203,718 disclose a common mode choke coil that is an example of the thin-film type coil component. This common mode choke coil is formed in general by laminating alternately insulation layers and coil layers on a ferrite substrate using a thin-film fabrication technology, by laminating a ferrite substrate thereon, by cutting the laminated layers and substrates to separate into individual chips each having a rectangular parallelepiped external shape, and then by plating external electrodes so that they are connected to internal electrode terminals exposed on side surfaces of the chip.
The conventional electronic components such as the above-mentioned common mode choke coils are fabricated as follows. First, a lot of elements are formed on a substrate using a thin-film fabrication technology, then the substrate is cut to separate into individual element chips, and thereafter external electrodes are formed by plating on a top surface, side surfaces and a bottom surface of each chip. In order to obtain enough strength in soldering joint with a printed circuit board and enough conductivity with inner conductors, the common mode choke coil described in Japanese patent publication No. 8-203,737 has a U-shaped cross-section pattern in each external electrode.
However, because no side surface of the chip will expose before cutting the substrate into the individual chips, it is impossible to make the external electrodes on the side surfaces before the cutting process. If no external electrode is formed on the side surfaces, an area of the electrodes becomes extremely small and thus enough strength cannot be ensured in soldering joint.
Therefore, when fabricating such electronic components, external electrode pattern with a desired cross-section shape is formed on surfaces of each chip after cutting the substrate into the individual chips. Since it is necessary to form the external electrode pattern after having separated into individual chips, according to the conventional art, it is very difficult to precisely form the shape, dimensions and position of each external electrode. In addition, according to the conventional art, because a plurality of fabrication processes such as a process for fabricating elements on a substrate and a process performed after the separation of the substrate into individual chips are necessary, the manufacturing cost will be extremely increased.